Fiber suspension distribution system



C. A. LEE ET FIBER SUSPENSION DISTRIBUTION SYSTEM May 20, 1969 SheetFiled Aug. 16, 1965 /4/t E4/ r015 l'lAfLf dun (Arc J4 s ,4, lfvrmr Br W,M, ya, a

May 20, 1969 LE ETAL FIBER SUSPENSION DISTRIBUTION SYSTEM I Sheet 2 014Filed Aug. 16, 1965 m s r M 4H 4. M M M J 0 N5, mm NEAMWWNMMWHWKQM Q C 3L W M: mm

May 20, 1969 c. A. LEE ETAL 3,445,331

FIBER SUSPENSION DISTRIBUTION SYSTEM Filed Aug. 16, 1965 Sheet 3 014 'II II 1| 1 l- I I I I II to QrL May 20, 196% Q; LEE ETAL 3,445,331

FIBER SUSPENSION DISTRIBUTION SYSTEM Filed Aug. 1a. 1965 Sheet 4 of 4IIII'I'II vli'llllllllllil I M 'l'lllllllll OX /M/4/ra(5 (Hails-5 flan:(5

United States Patent Office 3,445,331 Patented May 20, 1969 FIBERSUSPENSION DISTRIBUTION SYSTEM Charles Allen Lee, Knoxville, Tenn., andJames A. Murphy, Toronto, Ontario, Canada, assignors, by direct andmesne assignments, to Canadian International Paper Company, Montreal,Quebec, Canada, a body corporated and politic Filed Aug. 16, 1965, Ser.No. 479,797 Int. Cl. D21f 1/06 U.S. Cl. 162-338 7 Claims ABSTRACT OF THEDISCLOSURE A movable distribution system for a paper making machineincluding a mixing chamber with a plurality of orifices distributed overits area. The total cross-sectional area of flow at the inlet end of themixing chamber is intermediate the cross-sectional area of the mixingchamber and the total cross-sectional area of said orifices.

This invention relates to a distribution system for supplying asuspension of papermaking fibers to the headbox of a papermakingmachine, and more particularly to a distribution system in which thesuspension is introduced through a plate having a plurality of orificesinto a headbox having a plurality of tubes at its inlet end.

In making paper, it is ordinarily desirable that the paper be madeuniform. This requires that the papermaking fibers be laid downuniformly upon the papermaking wire on which the paper is formed. Inorder to lay the fibers down uniformly, it is generally necessary that ahomogeneous suspension of fibers be evenly distributed across the wirefrom a headbox. In order that the flow from the headbox be uniformacross the width of the wire, it is helpful if the inlet into theheadbox provides for uniform distribtuion of the fibers and that thefibers be uniformly distributed in the incoming fluid.

The present invention is directed to a distribution system fordelivering a substantially homogeneous mixture of paper fibers in anaqueous suspension projected into the headbox substantially uniformlyacross its inlet, most particularly when the headbox is of the typehaving a plurality of parallel tubes at its inlet end, through which theincoming suspension flows.

In headboxes of the prior art, it is known to utilize a bank ofsubstantially parallel tubes uniformly distributed in the inlet of theheadbox to stabilize the flow of turbulent fluid. One such headbox isshown in Bennett Canadian Patent No. 503,957, which describes theoperation of the headbox to establish the condition of frozen fiow. Insuch headboxes, the suspension was introduced into each tube through anorifice in a plate closing the inlet end of each tube.

In earlier distribution systems, it has been the practice, as shown inthe aforesaid Bennett patent, to supply the fiber suspension to theorifices through a number of inlet tubes. The tubes were relatively fewin number, for example six, and the flow from the inlet tubes was inseparate streams each flowing directly against a particular section ofthe plate. The orifices directly in the path of the streams readilypassed the suspension at a relatively high rate whereas the orifices notin the direct path of any stream passed the suspension only after adevious route and loss of energy and consequently at a relatively lowerrate. This resulted in a non-uniform distribution of flow through therespective tubes. This in turn resulted in a non-uniform flow of fluidfrom the headbox and hence non-uniform distribution of fibers on thewire.

A further difficulty with the distribution system previously used forheadboxes of the type having a bank of tubes in its inlet end was thegreat difiiculty in keeping the tubes clean. More particularly, on shutdown fibers often collected in the pockets created by the plates closingthe ends of the tubes. Fibers also collected at other places in thedistribution system, as in the inlet tubes to the mixing; chamber of thesystem. Such collections of fibers were released from time to time intothe flow, hence producing non uniformity.Non-uniformity was alsoproduced when the fiber suspension was changed. For example, on mostpapermaking machines it is on occasion necessary or desirable to changethe type or color of the stock. In the case of color changes or whenproducing changes of type, it is often intolerable to have fibers of thewrong color or type mixed in with the proper fibers, and it thereforemay be necessary that the headbox be cleaned when changing from onecolor or type of paper to another. Under such circumstances, thecleaning of the distribution systems of the prior art has encountereddifficulties and delays.

To overcome the non-uniformities occasioned by nonuniform distributionof flow through the orifices, the suspended fibers may be introducedinto a mixing chamber substantially uniformly across the chamber with arelatively negligible component of flow in the cross direction of thechamber. The suspension is mixed by deflecting the entering suspension,and then forcing the mixed fibers through a plurality of small holes ina distribution plate, the holes being substantially uniformlydistributed across the entire width of the headbox. These small streamspass into the inlet of the headbox. The total cross-sectional area ofthe inlet to the mixing chamber is less than the cross-sectional area ofthe mixing chamber but greater than the total cross-sectional area ofthe orifices. Under these conditions of changing direction of flow andchanging cross section of flow, the fiber suspension is substantiallyuniformly mixed within the mixing chamber and is discharged through theorifices under substantially uniform conditions of turbulence atsubstantially uniform rates of flow through the respective orifices.

In the case of the headbox having a bank of tubes in its inlet end,there is a single orifice disposed centrally of each tube in theheadbox. The distribution system of this invention thus provides thesame flow of fiber suspension through each tube in the inlet of theheadbox.

For the purpose of cleaning the headbox and particularly the tubes inthe inlet thereof, the distribution plate is made readily removable.Further, the plate in its op erating position is not disposed againstthe ends of the headbox tubes but rather is disposed a short distanceaway, this distance being such that the jet of fluid through eachorifice passes centrally into a respective tube while producing backwardflowing vortex rings or eddy currents outside the jet to clean the inletends of the respective tubes. This distance should be larger than aboutinch in order that the fiber suspension is free to move between the endsof the tubes and the distribution plate rather than being trapped andcaught in a pocket; however, this distance should not be so great as topermit the jet to strike the ends of the tubes.

Not only is the distribution plate made easily removable, but the entiremixing chamber is made readily removable in order that the inlet intothe chamber can be cleaned.

It is therefore a primary object of this invention to provide adistribution system for supplying a turbulent homogeneous suspension ofpapermaking fibers uniformly across the inlet of the headbox of apapermaking machine. Another object of the invention is to provide sucha distribution system in which the fluid is supplied through a pluralityof orifices in a perforated distribution plate with the flow from eachorifice being directed into a respective tube in the inlet of theheadbox.

Still another object of the invention is to provide such a distributionsystem in which the distribution plate is placed such a distance fromthe inlet ends of the tubes that the jets of fiber suspension throughthe distribution plate cleanses the tubes rather than permitting fibersto collect at their inlet ends.

Still another object of the invention is to provide a mixing chamber anddistribution plate readily removable from the inlet end of the headboxto facilitate cleaning of the headbox and the distribution system,including the inlet thereto, and to permit quick and simple changing ofthe orifice size merely by changing the distribution late. p Otherobjects and advantages of the invention will become apparent fromconsideration of the following detailed description, particularly whentaken in conjunction with the accompanying drawings in which:

FIGURE 1 is a side elevation, partly in section, of a headbox for apapermaking machine, showing its association with a preferred form of astock distribution system according to the present invention;

FIGURE 2 is an enlarged view, partly in section, of the distributionsystem shown in FIGURE 1 as secured to the headbox, and showing indashed lines the position of the mixing chamber of the distributionsystem when retracted from the headbox;

FIGURE 3 is an elevation of the other side of the machine showing themanner in which the mixing chamber is moved;

FIGURE 4 is an end elevation view, partly in section, taken along thesection 4-4 of FIGURE 2, showing the distribution system;

FIGURE 5 is a sectional view, taken along the section 5-5 of FIGURE 4,showing the mixing chamber, with a distribution plate affixed thereto,mounted in place on the headbox;

FIGURE 6 is a sectional view showing the same apparatus as FIGURE 5, butwith the mixing chamber and distribution plate slightly retracted fromthe headbox;

FIGURE 7 is an end elevation of a number of the tubes in the inlet ofthe headbox shown in FIGURE 1, showing by dashed lines the relationshipof the orifices in the distribution plate; and

FIGURE '8 is a sectional view, taken along section 88 of FIGURE 7,showing the relationship between the distribution plate and the tubes inthe headbox.

In FIGURE 1 is shown a papermaking machine including a distributionsystem 8 of the present invention. The distribution system is at theinlet end of a head-box 9. The headbox 9 comprises an upwardly slantingrectangular channel portion 10. The interior of the channel portion 10contains a plurality of relatively small, straight tubes 11 disposedparallel to the longitudinal axis of the channel 10. As shown best inFIGURE 7, the tubes may be hexagonal in cross section so as to fill thechannel portion 10 in honeycomb fashion. Other cross sections, such asround or square, may be used. The channel 10 and, indeed, the entireheadbox 9 is of substantially the same width as wire 12 upon which thestock suspension 13 is deposited to form the paper web. The inlet endsof the tubes are disposed substantially in a plane. At the upper oroutlet end of the tubes the tubes may be of varying lengths, asillustrated, with the lowermost tier being the longest and the uppermosttier being the shortest. The length of the tubes relative to theirdiameter is such as to provide the condition of the suspension 13necessary to produce the stabilization of flow.

The upper or discharge end of the channel 10 joins a relatively long,horizontally disposed channel portion 15 formed from metal plates havinga smooth inner surface and provided at its discharge end with anadjustable slice assembly diagrammatically indicated at 16. The sliceassembly 16 itself may be of any suitable construction and may include aslice lip and an apron between which the suspension 13 flows out of theheadbox 9 onto the wire 12.

While the mechanical details per se of the slice mechanism form no partof the present invention, it will be appreciated that its constructionmay be of such a nature that the assembly which has generally beenindicated at 16 includes stationary mounting elements 19 whichslidea'bly support slice lip carrying elements 20 adapted to beadjustably positioned in any desired operating location as by adjustingscrew and hand wheel assemblies generally indicated at 21.

In the illustrated embodiment of the invention, the headbox is shown asit would be fabricated to operate as a pressure headbox in which thedepth of flow of the fiber suspension in the horizontal channel 15 isless than the overall depth of the channel. When such a design isemployed, means are provided for maintaining air pressure in thatportion of the channel 15 above the flowing fiber suspension and in thepresent instance comprises an inlet pipe 22 opening into the channel 15and connected with a suitable source (not shown) of compressed air. Inorder that proper control may be effected on the stock flowing under airpressure through the channel 15, including control of the depth of flowand the corresponding velocity of the stock in the channel, a bleederpipe 23 of relatively small diameter is afiixed to one wall of and opensinto the channel 15 at a height substantially equal to the designeddepth of flow of the stock suspension. An adjustable valve 24 generallywill be provided so as to restrict the leakage of compressed air, andthe discharge side of the valve 24 may be connected to the wire pit ofthe paper machine. If an open headbox is used, the fluid level in theheadbox is of course greater.

In many papermaking machines the suspension 13 is deposited upon thewire 12 in a turbulent condition. The turbulence tends to keep thefibers from floccing together by the shearing action of eddy currents.Although the turbulence prevents excessive fioc formation, the turbulentflow out of the slice orifice disturbs the uniform formation of thepaper web. It is for this reason that frozen flow from the slice issometimes desired. Frozen or plug flow is characterized by a thin shearzone adjacent to any surface of the channel contacted by the stock inwhich the fibers tend to roll or shear past one another, while all therest of the cross section of the flowing suspension appears to be frozeninto a solid plug, moving parallel to the axis of the channel and withuniform velocity throughout its cross section. With little or nomovement of the fibers in relation to one another within a frozen flow,the gathering together of the fibers into flocs takes place very slowlyor not at all.

Under some operating conditions, some flocculation of the fibers mayoccur, resulting in a floc pattern which may be retained through theslice orifice and in the paper. In the event that this floc patterncontains flocs of objectionably large size, there may be provideddesirably a rotatable cage-type defloccing roll 25 transverselypositioned within the horizontal channel 15 at either of the positionsshown and driven by suitable power connections (not shown).

The headbox just described is well known. The improvement of the presentinvention lies in the distribution system 8 which supplies the fibersuspension to the headbox and in the manner in which the distributionsystem is coupled to the headbox. The distribution system 8 is shown ingreater detail in FIGURES 2 and 4. The distribution system includes amanifold 26 into which the fiber suspension is pumped at the large end.The pressure in the manifold drives the fluid upwardly through a numberof inlet tubes 28 into a mixing chamher 30, whence it passes through aperforated distribution plate 32 into the headbox 9. The distributionplate covers the outlet end of the mixing chamber.

In order that the distribution system and the headbox can be cleanedeasily, the mixing chamber is made removable. To this end the walls 33defining the chamber are mounted on rollers or wheels 34 for movementalong tracks 36. As shown best in FIGURE 3, the walls defining themixing chamber are moved along the track by operation of a hand operatedwheel 38 operating through gears to drive a chain 40 to turn a gear 42which in turn is coupled to gears 44 which mesh with racks 46 to drivethe mixing chamber along the tracks 36. A shaft 48 couples the gears 44together. The tracks are preferably horizontal in order that theapparatus can be easily moved without having to overcome the force ofgravity.

The removable mounting of the mixing chamber is best observed bycomparing FIGURES and 6. The mixing chamber 30 is shown mounted inoperating position in FIGURE 5, while in FIGURE 6 it is shown slightlyretracted. When in place, the walls 33 form an enclosed housing closedin part by the stationary base member 52. The mixing chamber 30 isclosed at its ends by end plates 54 and is sealed by seals 56. The seals56 may be hydraulically operated so that the mixing chamber housing 50and end plates 54 may be secured in place by bolts 58 and 60 before thetight seal is made.

When the mixing chamber is in operating condition as shown in FIGURE 5,the fiber suspension passes upwardly through the inlet tubes 28 into themixing chamber 30 and thence through orifices 62 in the distributionplate 32. Each orifice is disposed centrally of a respective tube 11, asindicated more specifically in FIGURES 7 and 8. When in operatingposition, the distribution plate 32 is mounted a short distance from theinlet ends of the tubes 11, the ends of the tubes 11 lying substantiallyin a plane parallel to the distribution plate and with the tubes 11extending perpendicular to this plane. For the sake of adjustment andsupport, a plurality of spacer screws 64 are mounted in the distributionplate 32 and protrude therefrom toward the inlet tubes 11 by apredetermined amount. These spacer screws serve to determine the amountby which the distribution plate 32 is spaced from the tubes 11.Additionally, these spacer screws 64 also serve to hold the distributionplate 32 away from the tubes 11 during operation, for when the fibersuspension is forced into the mixing chamber 30, the pressure on thedistribution plate 32 bows it toward the tubes 11.

For optimum performance, the relative sizes of the various componentsand their relative disposition are somewhat critical. The size and shapeof the manifold 26 is such as to maintain substantially the samepressure at the inlet of each of the inlet tubes 28. The fibersuspension is introduced at the large end of the manifold 26. This endmay be 24 inches in diameter. The diameter of the manifold 26 decreasestoward the narrow end at such rate as to compensate for the decrease inthe horizontal fluid flow occasioned by the extraction of fluid throughthe earlier inlet tubes 28. By this means the linear rate of flow ismaintained constant to prevent the increase in pressure that wouldotherwise be occasioned by the slowing down of the fluid in the manifold26. The flow of fluid from the small end of the manifold 26 may becontrolled to aid in the balancing of pressures at the inlet ends of theinlet tubes 28 to provide for equal flow through each tube.

Relatively large numbers of inlet tubes pass from the manifold 26 to themixing chamber 30. As shown, twentyfive inlet tubes have provedsatisfactory, each of a diameter of about 2 /2 inches. In the prior art,it has been known to use six inlet tubes of larger diameter. However,the larger number of inlet tubes provides for greater homogeneity in themixing chamber. That is, with the relatively large number of inlet tubes28 the fiber suspension is introduced into the mixing chambersubstantially uniformly across its inlet end. There is a sufiicientnumber of inlet tubes sufliciently close together that the jets emittedfrom the tops of the inlet tubes 28 promptly merge by the turbulencecreated by the jets. These inlet tubes 28 are preferably relatively longto reduce any cross flow pattern within the individual tubes, so thatthe flow is substantially entirely lengthwise of the tubes. The tubes 28are preferably straight and are substantially parallel at their entranceinto the mixing chamber 30 in order that there be substantially nocomponent of flow in the cross direction of the chamber 30.

Proper flow into the mixing chamber may be achieved by use ofalternative inlets. For example, a flow spreader may be interposedbetween the single large round pipe at the inlet to the manifold 26 andthe mixing chamber. This flow spreader could convert the flow from asingle concentrated stream to a single flat stream evenly distributedacross the entire inlet side of the mixing chamber and all flowing inthe machine direction with substantially no component of flow in thecross direction of the chamber.

In the prior art, the output from the inlet tubes moved in jets towardthe tubes 11 thus driving more of the suspension into some of the tubesthan others. To avoid this the incoming jets from the tubes 28 do notmove directly toward the orifices 62 but rather are forced to make asubstantial change in direction and to mix with the fluid previously inthe chamber 30 before leaving through the orifices 62. The fluid may bedirected, as shown, generally toward the top of the housing anddeflected by the wall 33 and the fluid previously in the mixing chamber30. The mixing chamber 30 thus produces turbulence in the suspension andprovides substantially uniform distribution of the fibers in the fluid.It is in this state that the fluid moves through the distribution plate32.

In the preferred form of the invention, the total crosssectional area ofall of the orifices 62 in the distribution plate 32 is less than thetotal cross-sectional area of the inlet tubes 28, which in turn issmaller than the crosssectional area of the flow through the mixingchamber between the inlet tubes 28 and the outlet orifices 62. This aidsin the production of the desired amount of turbulence.

The desired size of the orifices 62 depends on a number of factorsincluding the number and size of the tubes 11. With tubes of about 2 /2inches in diameter, orifices of about inch have proven suitable.Similarly, the desired spacing between the distribution plate and theinlet ends of the tubes 11 depends upon several factors. With inchorifices and 2 /2 inch tubes about inch spacing has proven satisfactory.It is desirable that the distribution plate 32 be fiat and have theorifices 62 substantially perpendicularly therethrough in order that thejets 66 produced by the flow of fluid through the orifices 62 be in thedirection of the tubes 11. Preferably the inlet ends of the orificeshave rounded edges so as not to wear excessively.

As previously mentioned, it is important that fibers not collect in theinlet end of the tube.- If fluid flowed against the inlet edges 68 ofthe tubes 11, they would tend to staple or wrap around the edges andaccumulate fibers. By spacing the distribution plate 32 at the properdistance from these edges 68, the jets of fiber suspension 66 actuallywash away any fibers that happen to collect. That is, the entering jets66 drive the fluid suspension into the centers of the tubes 11, andthese forward moving streams do not strike the walls of the tubes 11until some distance from the inlet ends 68. In the intervening regionthe jets create turbulence in the nature of vortex rings or eddycurrents 70 which provide a reverse flow along the insides of the tubestoward their inlet end, thus washing away any fibers tending to collecton the edges 68. Typically, the spacing between the distribution plate32 and the edges 68 of the tubes 11 should be larger than about /1 inchin order that the fibers may pass freely through this space and not betrapped. At the same time the spacing must be short enough that theedges 68 are in the region of reverse flow or vortex rings 70. A spacingof about two orifice diameters has proven suitable.

Although the tubes 11 are thus self-cleansing with the distributionsystem of the present invention, the distribution system is additionallymade particularly suitable for cleaning by reason of being easilyremovable from the headbox. The mixing chamber 30 may be readily movedupon the tracks 36 by operation of the wheel 38 after the bolts 58 and60 have been released. This exposes the inlet ends of the tubes 11 inthe tube bank for swabbing. It also exposes the vertical inlet tubes 28for sWabbing. The distribution plate 32 is itself demountable from thewalls 33 for cleaning on both sides and also permitting the cleaning ofthe interior of the walls 33. As noted earlier, such cleaning of thedistribution system and headbox is often necessary when changing thetype or color of the fiber suspension. In practice, it has been foundthat the system of the present invention can be cleaned in less than 20percent of the time needed to clean the distribution system and headboxof the prior art devices where the headbox tubes were individuallycovered by permanently installed plates Further, the distribution platemay be changed for one having orifices of different diameter, as may bedesirable for operating at different speeds. This provides greaterflexibility to the overall operation of the papermaking machine.

A patent is solicited for any and all herein disclosed patentablesubject matter invented by applicants.

The embodiment particularly disclosed herein may be changed or modifiedin various ways without departing from the scope of the invention.

Various features now believed to be new and patentable are set forth inthe appended claims.

What is claimed is:

1. A distribution system for supplying a fiber suspension to the inletend of a headbox of a papermaking machine, said distribution systemcomprising wall means defining a mixing chamber of substantially thesame width as said inlet end of said headbox and having an outlet endand an inlet end of substantially said same width, a perforateddistribution plate mounted on said wall means to cover said outlet endof said mixing chamber and having a multiplicity of orifices ofsubstantially the same size substantially uniformly distributed over thearea of said plate and extending in the same direction through saidplate for admitting said fiber suspension from said mixing chamber intosaid headbox in a plurality of jets moving in the same direction, amultiplicity of substantially parallel inlet tubes of substantiallyequal diameter coupled to said inlet end of said mixing chamber, andmanifold means for supplying said fiber suspension at substantiallyequal rates to each of said inlet tubes, said inlet tubes beingsubstantially uniformly spaced across said inlet end of said mixingchamber sufiiciently close together that said fiber suspension isintroduced into said mixing chamber substantially uniformly across itsinlet end, said inlet tubes being sufficiently long and extending insuch direction that said fiber suspension issues therefrom into saidmixing chamber in the same direction which same direction differssubstantially from the direction of flow of said fiber suspensionthrough said orifices and with a relatively negligible component of flowin the cross direction of said mixing chamber, and the totalcross-sectional area of said inlet tubes being intermediate thecross-sectional area of said mixing chamber and the totalcross-sectional area of said orifices, whereby said fiber suspension issubstantially uniformly mixed within said mixing chamber and isdischarged in substantially uniform turbulent conditions atsubstantially uniform rates through the respective orifices into saidheadbox.

2. A distribution system for supplying a fiber suspension to the inletend of a headbox of a papermaking machine, said distribution systemcomprising wall means defining a mixing chamber of substantially thesame width as said inlet end of said headbox and having an outlet endand an inlet end, said Wall means being mounted upon a movable carriage,a perforated distribution plate removably mounted on said wall means tocover said outlet end of said mixing chamber and having a multiplicityof orifices of substantially the same size substantially uniformlydistributed over the area of said plate and extending in the samedirection through said plate for admitting said fiber suspension fromsaid mixing chamber into said headbox in a plurality of jets moving inthe same direction, means coupled to said carriage for moving saidcarriage with said Wall means and distribution plate mounted thereonfrom a first position remote from said inlet end of said headbox to asecond position wherein said distribution plate is disposed at saidinlet end of said headbox, and inlet means for coupling to said inletend of said mixing chamber to introduce said fiber suspension into saidinlet end of said mixing chamber, the total cross-sectional area of saidinlet means being intermediate the cross-sectional area of said mixingchamber and the total cross-sectional area of said orifices, wherebysaid fiber suspension is substantially uniformly mixed within saidmixing chamber and is discharged in substantially uniform turbulentconditions at substantially uniform rates through the respectiveorifices into said headbox.

3. A distribution system for supplying a fiber suspension to the inletend of a headbox of a papermaking machine, said distribution systemcomprising wall means defining a mixing chamber of substantially thesame Width as said inlet end of said headbox and having an outlet endand an inlet end of substantially said same width, said wall means beingmounted upon a movable carriage, a perforated flat distribution plateremovably mounted on said wall means to cover said outlet end of saidmixing chamber and having a multiplicity of round orifices ofsubstantially equal diameter substantially uniformly distributed overthe area of said plate and extending normally through said plate foradmitting said fiber suspension from said mixing chamber into saidheadbox in a plurality of jets moving in the same direction, amultiplicity of substantially parallel inlet tubes of substantiallyequal cross section for coupling to said inlet end of said mixingchamber, means coupled to said carriage for moving said carriagehorizontally with said wall means and distribution plate mounted thereonfrom a first position remote from said inlet end of said headbox to asecond position wherein said distribution plate is disposed at saidinlet end of said headbox and substantially perpendicular to thedirection of flow in said inlet end of said headbox, and wherein saidinlet tubes are coupled to said inlet end of said mixing chamber, andmanifold means for supplying said fiber suspension at substantiallyequal rates to each of said inlet tubes, said inlet tubes beingsubstantially uniformly spaced across said inlet end of said mixingchamber sutficiently close together that said fiber suspension isintroduced into said mixing chamber substantially uniformly across itsinlet end, said inlet tubes being sufiiciently long and extending insuch direction that said fiber suspension issues therefrom into saidmixing chamber in the same direction which same direction differssubstantially from the direction of flow of said fiber suspensionthrough said orifices and with a relatively negligible component of flowin the cross direction of said mixing chamber, and the totalcross-sectional area of said inlet tubes being intermediate thecross-sectional area of said mixing chamber and the totalcross-sectional area of said orifices, whereby said fiber suspension issubstantially uniformly mixed within said mixing chamber and isdischarged in substantially uniform turbulent conditions atsubstantially uniform rates through the respective orifices into saidheadbox.

4. A distribution system for supplying a fiber suspension to the inletend of a headbox of a papermaking machine, said inlet end of saidheadbox having a multiplicity of substantially straight and parallelheadbox tubes substantially uniformly distributed over said inlet end ofsaid headbox for stabilizing the flow within said headbox, saiddistribution system comprising -wal1 means defining a mixing chamber ofsubstantially the same Width as said inlet end of said headbox andhaving an outlet end and an inlet end, said wall means being mountedupon a movable carriage, a perforated distribution plate removablymounted on said wall means to cover said outlet end of said mixingchamber and having a multiplicity of orifices of substantially the samesize each corresponding to one of said headbox tubes to admit said fibersuspension from said mixing chamber into said corresponding one of saidheadbox tubes, the cross section of each orifice being small relative tothe cross section of each of said headbox tubes, means coupled to saidcarriage for moving said carriage with said wall means and distributionplate mounted thereon from a first position remote from said inlet endof said headbox to a second position wherein said distribution plate isdisposed substantially perpendicular to said headbox tubes and spacedtherefrom by a distance permitting said fiber suspension to move freelybetween the ends of said headbox tubes and said distribution plate withsaid orifices disposed substantially centrally of said correspondingheadbox tubes and with the inlet end of each headbox tube within theregion of reverse flow occasioned by the jet of fluid through arespective orifice, and inlet means for supplying said fiber suspensionto said inlet end of said mixing chamber, and the total cross-sectionalarea of said inlet means being intermediate the cross-sectional area ofsaid mixing chamber and the total cross-sectional area of said orifices,whereby said fiber suspension is discharged in substantially uniformturbulent conditions at substantially uniform rates through therespective orifices into the center of corresponding ones of saidheadbox tubes.

5. A distribution system for supplying a fiber suspension to the inletend of a headbox of a papermaking machine, said inlet end of saidheadbox having a multiplicity of substantially straight and parallelheadbox tubes substantially uniformly distributed over said inlet end ofsaid headbox for stabilizing the flow within said headbox, saiddistribution system comprising wall means definng a mixing chamber ofsubstantially the same width as said inlet end of said headbox andhaving an outlet end and an inlet end, a perforated distribution platemounted on said wall means to cover said outlet end of said mixingchamber and having a multiplicity of orifices of substantially the samesize extending through said plate in a direction parallel to saidheadbox tubes and each disposed substantially centrally of acorresponding one of said headbox tubes to admit said fiber suspensionfrom said mixing chamber into said corresponding one of said headboxtubes, the cross section of each orifice being small relative to thecross section of each of said headbox tubes, said distribution platebeing spaced from said headbox tubes by a distance permitting said fibersuspension to move freely between the ends of said headbox tubes andsaid distribution plate with the inlet end of each headbox tube withinthe region of reverse flow occasioned by the jet of fluid through arespective orifice, and inlet means for supplying said fiber suspensionto said inlet end of each mixing chamber, the total cross-sectional areaof said inlet means being intermediate the cross-sectional area of saidmixing chamber and the total cross-sectional area of said orifices,whereby said fiber suspension is discharged in substantially uniformturbulent conditions at a substantially uniform rates through therespective orifices into the center of corresponding ones of saidheadbox tubes.

6. A distribution system for supplying a fiber suspension to the inletend of a headbox of a papermaking machine, said inlet end of saidheadbox having a multiplicity of substantially straight and parallelheadbox tubes substantially uniformly distributed over said inlet end ofsaid headbox for stabilizing the flow within said headbox, saiddistribution system comprising wall means defining a mixing chamber ofsubstantially the same width as said inlet end of said headbox andhaving an outlet end and an inlet end of substantially said same width,a perforated flat distribution plate mounted on said wall means to coversaid outlet end of said mixing chamber and having a multiplicity ofround orifices of substantially equal diameter extending through saidplate in a direction parallel to said headbox tubes and each disposedsubstantially centrally of a corresponding one of said headbox tubes toadmit said fiber suspension from said mixing chamber into saidcorresponding one of said headbox tubes, the cross section of eachorifice being small relative to the cross section of each of saidheadbox tubes, said distribution plate being disposed substantiallyperpendicular to said headbox tubes and spaced therefrom by a distancepermitting said fiber suspension to move freely between the ends of saidheadbox tubes and said distribution plate with the inlet end of eachheadbox tube within the region of reverse flow occasioned by the jet offluid through a respective orifice, a multiplicity of substantiallyparallel inlet tubes of substantially equal cross section coupled tosaid inlet end of said mixing chamber, and manifold means for supplyingsaid fiber suspension at substantially equal rates to each of said inlettubes, said inlet tubes being substantially uniformly spaced across saidinlet end of said mixing chamber sufiiciently close together that saidfiber suspension is introduced into said mixing chamber substantiallyuniformly across its inlet end, said inlet tubes being sufliciently longand extending in such direction that said fiber suspension issuestherefrom into said mixing chamber in the same direction which samedirection differs substantially from the direction of flow of said fibersuspension through said orifices and with a relatively negligiblecomponent of flow in the cross direction of said mixing chamber, and thetotal cross-sectional area of said inlet tubes being intermediate thecrosssectional area of said mixing chamber and the total crosssectionalarea of said orifices, whereby said fiber suspension is substantiallyuniformly mixed within said mixing chamber and is discharged insubstantially uniform turbulent conditions at substantially uniformrates through the respective orifices into the center of correspondingones of said headbox tubes.

7. A distribution system for supplying a fiber suspension to the inletend of a headbox of a papermaking machine, said inlet end of saidheadbox having a multiplicity of substantially straight and parallelheadbox tubes substantially uniformly distributed over said inlet end ofsaid headbox for stabilizing the flow within said head box, saiddistribution system comprising wall means defining a mixing chamber ofsubstantially the same width as said inlet end of said headbox andhaving an outlet end and an inlet end of substantially said same width,said Wall means being mounted upon a movable carriage, a perforated fiatdistribution plate removably mounted on. said wall mearns to cover saidoutlet end of said mixing chamber and having a multiplicity of roundorifices of substantially equal diameter each corresponding toone ofsaid headbox tubes to admit said fiber suspension from said mixingchamber into said corresponding one of said headbox tubes, each orificehaving a cross section small relative to the cross section of each ofsaid headbox tubes and extending normally through said plate, amultiplicity of substantially straight and parallel inlet tubes ofsubstantially equal cross section for coupling to said inlet end of saidmixing chamber, means coupled to said carriage for moving said carriagehorizontally with said wall means and distribution plate mounted thereonfrom a first position remote from said inlet end of said headbox to asecond position wherein said distribution plate is disposedsubstantially perpendicular to said headbox tubes and spaced therefromby a distance permitting said fiber suspension to move freely betweenthe ends of said headbox tubes and said distribution plate with saidorifices disposed substantially centrally of said corresponding headboxtubes and with the inlet end of each headbox tube within the region ofreverse flow occasioned by the jet of fluid through a respective orificeand wherein said inlet tubes are coupled to said inlet end of saidmixing chamber, and manifold means for supplying said fiber suspensionat substantially equal rates to each of said inlet tubes, said inlettubes being substantially uniformly spaced across said inlet end of saidmixing chamber sufficiently close together that said fiber suspension isintroduced into said mixing chamber substantially uniformly across itsinlet end, said inlet tubes being sufficiently long and extending insuch direction that said fiber suspension issues therefrom into saidmixing chamber in the same direction which same direction differssubstantially from the direction of flow of said fiber suspensionthrough said orifices and with a relatively negligible component of flowin the cross direction of said mixing chamber, and the totalcross-sectional area of said inlet tubes being intermediate the crosssectional area of said mixing chamber References Cited UNITED STATESPATENTS 3,098,787 7/ 1963 Sieber 162343 X DONALL H. SYLVESTER, PrimaryExaminer.

A. C. HODGSON, Assistant Examiner.

US. Cl. X.R. 162336, 343

